Can you show the exact output of that command?
Depending on the speed of your machine, Welcome may take some time to start.
Note that the underlying yad tool of Welcome has some known problems with wayland. To find more info about this issue, can you also show the latest journal with command
eos-log-tool -j
Note: you may want to check the journal output first before sharing it to a pastebin. You can do so by clicking the Save button first. If you are OK with the contents, run the command again, Share the logs, and show the returned URL here.